Too Much Negative Offset?

Tires and rims is always coming up. Discuss these item here!

Moderators: notoptoy, S Allen, Solex68

User avatar
Alvin
Roadster Nut-Site Supporter
Posts: 8288
Joined: Tue Jan 23, 2007 7:01 pm

Re: Too Much Negative Offset?

Post by Alvin »

Rutty wrote: Sun Apr 23, 2023 12:56 pm So I picked them up yesterday. The price wasn't bad so I took a chance. The good news is they're 14x5.5 and not 6.5. The bad news is the backspace is not 3.5 but 3. So that puts them at an offset of -6.4mm. With the 185 tires on them they are just hitting the rear fender. If I would get 175 tires and roll the fenders they might work. I like them but am not sure if they're worth the effort.
Matt,
That is great news on the sizing. The tire you have pictured is a 185 (SR) 14, which is equivalent to an 80-series sidewall...which is HUGE.

A 185/70/14 tire would be perfect, and solve your rear fender clearance. A 175 would also work.
Alvin Gogineni
San Jose, CA
1967.5 SPL/SR20
1997 Acura Integra GS-R
2022 Chevy Bolt EUV
zcarblog.com
Instagram
YouTube
My SR20 Build Thread
User avatar
redroadster
Roadsteraholic
Posts: 2411
Joined: Tue Mar 12, 2013 10:58 am
Location: KCMO
Model: 1500/1600
Year: High Windshield-68-70

Re: Too Much Negative Offset?

Post by redroadster »

JC Whitney last time I looked still had the helper springs , they are for a 620 pu but fit the 311 , they re arch the springs too a bit , not hard to install ,
Datsun dealer tech 76 to 87
Mitsubishi tech 9 yrs
Volvo, Kia, Toyota too
6 month - Rolls Royce
ASE MASTER TECH 96. - 11
70 SPL 86 Z31 T , Sportster
User avatar
Rutty
Roadster Fanatic
Posts: 94
Joined: Thu Nov 12, 2015 10:18 pm
Location: Minnesota

Re: Too Much Negative Offset?

Post by Rutty »

Alvin wrote: Sun Apr 23, 2023 3:45 pm
Rutty wrote: Sun Apr 23, 2023 12:56 pm So I picked them up yesterday. The price wasn't bad so I took a chance. The good news is they're 14x5.5 and not 6.5. The bad news is the backspace is not 3.5 but 3. So that puts them at an offset of -6.4mm. With the 185 tires on them they are just hitting the rear fender. If I would get 175 tires and roll the fenders they might work. I like them but am not sure if they're worth the effort.
Matt,
That is great news on the sizing. The tire you have pictured is a 185 (SR) 14, which is equivalent to an 80-series sidewall...which is HUGE.

A 185/70/14 tire would be perfect, and solve your rear fender clearance. A 175 would also work.
So you think that they'd clear the fenders with a smaller diameter tire? The ones on the rims now are really big. Probably 2" bigger in diameter than the 185/65R14 tires I have on the stock rims now.
Matt
'68 1600 (L20b)
'69 2000
Minnesota
User avatar
Rutty
Roadster Fanatic
Posts: 94
Joined: Thu Nov 12, 2015 10:18 pm
Location: Minnesota

Re: Too Much Negative Offset?

Post by Rutty »

redroadster wrote: Sun Apr 23, 2023 8:37 pm JC Whitney last time I looked still had the helper springs , they are for a 620 pu but fit the 311 , they re arch the springs too a bit , not hard to install ,
Are these the type of springs you're talking about redroadster? I didn't know these existed.
Matt
'68 1600 (L20b)
'69 2000
Minnesota
User avatar
rwmann
Roadster Fanatic-Site Supporter
Posts: 701
Joined: Wed Aug 20, 2008 6:11 am
Location: Port Washington, NY
Model: 2000
Year: High Windshield-68-70

Re: Too Much Negative Offset?

Post by rwmann »

205/60R14 tires easily fit within the rear fender and wheel tub on a 7" wide rim with -15mm offset.
Last edited by rwmann on Fri Apr 28, 2023 7:54 pm, edited 1 time in total.
User avatar
redroadster
Roadsteraholic
Posts: 2411
Joined: Tue Mar 12, 2013 10:58 am
Location: KCMO
Model: 1500/1600
Year: High Windshield-68-70

Re: Too Much Negative Offset?

Post by redroadster »

Rutty wrote: Mon Apr 24, 2023 9:24 am
redroadster wrote: Sun Apr 23, 2023 8:37 pm JC Whitney last time I looked still had the helper springs , they are for a 620 pu but fit the 311 , they re arch the springs too a bit , not hard to install ,
Are these the type of springs you're talking about redroadster? I didn't know these existed.
I don't see them anymore on JC Whitney's
But if you search datsun 620 helper springs or add a leaf , there quite a bit , my kit gave 2 or 3 as adda leafs ,I used only the short ones
Last edited by redroadster on Mon Apr 24, 2023 12:12 pm, edited 1 time in total.
Datsun dealer tech 76 to 87
Mitsubishi tech 9 yrs
Volvo, Kia, Toyota too
6 month - Rolls Royce
ASE MASTER TECH 96. - 11
70 SPL 86 Z31 T , Sportster
User avatar
Alvin
Roadster Nut-Site Supporter
Posts: 8288
Joined: Tue Jan 23, 2007 7:01 pm

Re: Too Much Negative Offset?

Post by Alvin »

Rutty wrote: Mon Apr 24, 2023 9:09 am
Alvin wrote: Sun Apr 23, 2023 3:45 pm
Rutty wrote: Sun Apr 23, 2023 12:56 pm So I picked them up yesterday. The price wasn't bad so I took a chance. The good news is they're 14x5.5 and not 6.5. The bad news is the backspace is not 3.5 but 3. So that puts them at an offset of -6.4mm. With the 185 tires on them they are just hitting the rear fender. If I would get 175 tires and roll the fenders they might work. I like them but am not sure if they're worth the effort.
Matt,
That is great news on the sizing. The tire you have pictured is a 185 (SR) 14, which is equivalent to an 80-series sidewall...which is HUGE.

A 185/70/14 tire would be perfect, and solve your rear fender clearance. A 175 would also work.
So you think that they'd clear the fenders with a smaller diameter tire? The ones on the rims now are really big. Probably 2" bigger in diameter than the 185/65R14 tires I have on the stock rims now.
Yes, I think your tires are way too wide and tall of a sidewall. I just entered in sizes to calculate overall diameter in Google and the difference is a 1.5"

185/SR/14 25.7"
185/70/14 is 24.2"

https://www.calculator.net/tire-size-calculator.html
Alvin Gogineni
San Jose, CA
1967.5 SPL/SR20
1997 Acura Integra GS-R
2022 Chevy Bolt EUV
zcarblog.com
Instagram
YouTube
My SR20 Build Thread
User avatar
Rutty
Roadster Fanatic
Posts: 94
Joined: Thu Nov 12, 2015 10:18 pm
Location: Minnesota

Re: Too Much Negative Offset?

Post by Rutty »

I had an old 175/70R14 mounted to one of the rims. The clearance is much better. I have 1/2" clearance now. If I'm calculating correctly I'd have 5mm less clearance if I went to a 185/65R14.
You do not have the required permissions to view the files attached to this post.
Matt
'68 1600 (L20b)
'69 2000
Minnesota
User avatar
Alvin
Roadster Nut-Site Supporter
Posts: 8288
Joined: Tue Jan 23, 2007 7:01 pm

Re: Too Much Negative Offset?

Post by Alvin »

Rutty wrote: Fri Apr 28, 2023 2:04 pm I had an old 175/70R14 mounted to one of the rims. The clearance is much better. I have 1/2" clearance now. If I'm calculating correctly I'd have 5mm less clearance if I went to a 185/65R14.
Nice work!
I'm surprised how beefy the sidewall is even with 175/70/14!

The 185/65/14 tire will have a slightly shorter sidewall at the expense of a wider footprint. Less "ballooning" of the sidewall past the edge of wheel, if that makes sense. From the tire calculator:
Tire Height (Diameter) 23.6 in 601 mm 23.5 in 596 mm
Sidewall Height 4.8 in 123 mm 4.7 in 120 mm
Tire Width 6.9 in 175 mm 7.3 in 185 mm
Alvin Gogineni
San Jose, CA
1967.5 SPL/SR20
1997 Acura Integra GS-R
2022 Chevy Bolt EUV
zcarblog.com
Instagram
YouTube
My SR20 Build Thread
User avatar
Rutty
Roadster Fanatic
Posts: 94
Joined: Thu Nov 12, 2015 10:18 pm
Location: Minnesota

Re: Too Much Negative Offset?

Post by Rutty »

Here's a 185/65R14. It has about .340" clearance. So roughly 4mm less clearance than the 175/70R14.
You do not have the required permissions to view the files attached to this post.
Matt
'68 1600 (L20b)
'69 2000
Minnesota
User avatar
Gregs672000
Roadster Fanatic-Site Supporter
Posts: 9001
Joined: Fri Aug 07, 2009 11:47 pm
Location: Tacoma, WA

Re: Too Much Negative Offset?

Post by Gregs672000 »

I like the wheels. Would this be a good candidate for the 'ol fender roll? i.e. using a large wood dowel to roll the inner fender lip. I think you can cut a few small reliefs in the inside edge to help it roll up without stressing the paint, but I don't know if its required. You would gain a lot of clearance. Love the yellow and black together. I might consider painting the wheel centers black to get the fins to stand out and polish them up nice. And maybe black on the sides of the fins too...? The angled side view pic you posted made me think of it...
Greg Burrows
'67 2000 #588
Tacoma, WA
User avatar
Alvin
Roadster Nut-Site Supporter
Posts: 8288
Joined: Tue Jan 23, 2007 7:01 pm

Re: Too Much Negative Offset?

Post by Alvin »

Rutty wrote: Fri Apr 28, 2023 4:22 pm Here's a 185/65R14. It has about .340" clearance. So roughly 4mm less clearance than the 175/70R14.
I'm impressed by how many tire sizes you have access to!
175/65/14 will be your sweet spot...I know you have it :D
Alvin Gogineni
San Jose, CA
1967.5 SPL/SR20
1997 Acura Integra GS-R
2022 Chevy Bolt EUV
zcarblog.com
Instagram
YouTube
My SR20 Build Thread
User avatar
Rutty
Roadster Fanatic
Posts: 94
Joined: Thu Nov 12, 2015 10:18 pm
Location: Minnesota

Re: Too Much Negative Offset?

Post by Rutty »

Alvin wrote: Fri Apr 28, 2023 10:14 pm
Rutty wrote: Fri Apr 28, 2023 4:22 pm Here's a 185/65R14. It has about .340" clearance. So roughly 4mm less clearance than the 175/70R14.
I'm impressed by how many tire sizes you have access to!
175/65/14 will be your sweet spot...I know you have it :D
Hahaha! I have two roadsters, both with stock rims. One had the 185/65R14's and the other 175/70R14's.
I'll clean these aluminum rims up and have a new set of 170/70R14's put on them.
Matt
'68 1600 (L20b)
'69 2000
Minnesota
User avatar
Rutty
Roadster Fanatic
Posts: 94
Joined: Thu Nov 12, 2015 10:18 pm
Location: Minnesota

Re: Too Much Negative Offset?

Post by Rutty »

Gregs672000 wrote: Fri Apr 28, 2023 9:34 pm I like the wheels. Would this be a good candidate for the 'ol fender roll? i.e. using a large wood dowel to roll the inner fender lip. I think you can cut a few small reliefs in the inside edge to help it roll up without stressing the paint, but I don't know if its required. You would gain a lot of clearance. Love the yellow and black together. I might consider painting the wheel centers black to get the fins to stand out and polish them up nice. And maybe black on the sides of the fins too...? The angled side view pic you posted made me think of it...
Thanks!
I was thinking the same thing. Polish them up and paint the webbing and sides of the spokes black.
Matt
'68 1600 (L20b)
'69 2000
Minnesota
User avatar
Rutty
Roadster Fanatic
Posts: 94
Joined: Thu Nov 12, 2015 10:18 pm
Location: Minnesota

Re: Too Much Negative Offset?

Post by Rutty »

I found some time to start cleaning the rims and have a question. How clean do they have to be before paint will stick? I don't want to do them again in a few years, this is a lot of work!
Primed and painted one web area to see how well it sticks before I do them all.
You do not have the required permissions to view the files attached to this post.
Matt
'68 1600 (L20b)
'69 2000
Minnesota
Post Reply